Developers

API reference

Integrate fast, accurate UK address and postcode lookups. All endpoints return clean, structured JSON.

Base URLhttps://api.locatebase.com

Introduction

The Locatebase API is a simple, RESTful service for looking up and verifying UK addresses. Send a request to one of the endpoints below with your API key and receive a structured JSON response. All requests are made over HTTPS to https://api.locatebase.com.

Don't have a key yet? Create a free account to get started.

Authentication

Authenticate every request by passing your API key as the key query parameter. Keep your key secret and never expose it in client-side code you don't control.

Example

https://api.locatebase.com/postcode?postcode=SW1A%201AA&key=YOUR_API_KEY

Rate limits

Requests are limited to 100 requests per minute per IP address. If you exceed the limit you'll receive a 429 response. If you need a higher limit, get in touch.

Errors

The API uses standard HTTP status codes. Errors return a JSON body describing the problem.

400

Bad RequestA required parameter is missing or invalid. The response body lists the validation errors.

401

UnauthorizedThe API key is missing or invalid. Pass a valid key as the key query parameter.

402

Payment RequiredYour account has insufficient credits for the request.

429

Too Many RequestsRate limit exceeded (100 requests per minute, per IP).

500

Server ErrorAn unexpected error occurred. Retry shortly or contact support.

Response format

Successful lookups return a Meta object and a Results array. Each result contains the following fields.

Field

Type

Description

UPRN

string

Unique Property Reference Number for the address.

Address

string

Full, formatted single-line address.

BuildingNumber

integer

Building or house number, where present.

StreetName

string

Thoroughfare / street name.

Town

string

Post town.

Postcode

string

Postcode of the address.

Coordinates

object

Easting/northing (x, y) coordinates.

Status

string

Address record status, e.g. APPROVED.

Classification

string

Property classification code.

Custodian

string

Data custodian / authority.

CountryCode

string

Country indicator (E, S, W, N).

MatchQuality

number

Confidence score of the match (0–1).

MatchStatus

string

Match type, e.g. EXACT.

Example response

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/find

Address search

Search for addresses using a free-text query, such as a full or partial address.

Parameter

Type

Description

queryrequired

string

The free-text search query.

maxresultsoptional

integer

Maximum results to return (1–100). Defaults to 10.

countryCodeoptional

string

ISO country code to scope the search. Defaults to GB.

Request

curl "https://api.locatebase.com/find?query=10%20Downing%20Street&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/postcode

Postcode lookup

Return every address for a given postcode.

Parameter

Type

Description

postcoderequired

string

The postcode to look up.

maxresultsoptional

integer

Maximum results to return (1–100). Defaults to 10.

countryCodeoptional

string

ISO country code to scope the search. Defaults to GB.

Request

curl "https://api.locatebase.com/postcode?postcode=SW1A%201AA&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/uprn

UPRN lookup

Retrieve a single address by its Unique Property Reference Number (UPRN).

Parameter

Type

Description

uprnrequired

string

The UPRN identifying the property.

Request

curl "https://api.locatebase.com/uprn?uprn=100023336956&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/nearest

Nearest address

Find the nearest address to a coordinate point.

Parameter

Type

Description

latituderequired

string

Latitude of the point.

longituderequired

string

Longitude of the point.

countryCodeoptional

string

ISO country code. Defaults to GB.

Request

curl "https://api.locatebase.com/nearest?latitude=51.5014&longitude=-0.1419&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/bbox

Bounding box search

Return addresses within a rectangular bounding box. UK data only.

Parameter

Type

Description

bboxrequired

string

Bounding box as minX,minY,maxX,maxY (easting/northing).

Request

curl "https://api.locatebase.com/bbox?bbox=529000%2C179000%2C530000%2C180000&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

GET/radius

Radius search

Return addresses within a radius of a point. UK data only.

Parameter

Type

Description

pointrequired

string

Centre point as easting,northing.

radiusrequired

number

Radius in metres.

Request

curl "https://api.locatebase.com/radius?point=530047%2C179951&radius=100&key=YOUR_API_KEY"

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

POST/polygon

Polygon search

Return addresses within a custom GeoJSON polygon. UK data only.

Request body

application/json

{
  "type": "Polygon",
  "crs": {
    "type": "name",
    "properties": {
      "name": "EPSG:4326"
    }
  },
  "coordinates": [
    [
      [
        -0.1419,
        51.5014
      ],
      [
        -0.1409,
        51.5014
      ],
      [
        -0.1409,
        51.5024
      ],
      [
        -0.1419,
        51.5014
      ]
    ]
  ]
}

Request

curl -X POST "https://api.locatebase.com/polygon?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"type":"Polygon","crs":{"type":"name","properties":{"name":"EPSG:4326"}},"coordinates":[[[-0.1419,51.5014],[-0.1409,51.5014],[-0.1409,51.5024],[-0.1419,51.5014]]]}'

Response

200 application/json

{
  "Meta": {
    "Query": "SW1A 1AA",
    "Offset": 0,
    "TotalResults": 1
  },
  "Results": [
    {
      "UPRN": "100023336956",
      "Address": "10 Downing Street, London, SW1A 2AA",
      "BuildingNumber": 10,
      "StreetName": "DOWNING STREET",
      "Town": "LONDON",
      "Postcode": "SW1A 2AA",
      "Coordinates": { "x": 530047, "y": 179951 },
      "Status": "APPROVED",
      "Classification": "RD04",
      "Custodian": "GREATER LONDON AUTHORITY",
      "CountryCode": "E",
      "StateCode": "GB",
      "LastUpdate": "2024-02-10",
      "EntryDate": "2001-03-19",
      "Language": "EN",
      "MatchQuality": 1,
      "MatchStatus": "EXACT"
    }
  ]
}

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